Has the Control Key + Rotation snapping increment been changed or dropped?
If you choose to rotate with 5 degrees precision (or another transform operation), you should hold Ctrl while performing transform operation; if holding Ctrl and Shift rotation will happen by 1 degree. Snap during transform should be turned off, but its option Increment should be checked:



Transforming without precision will be done in case of other snapping option selected.

If you turn on Snap during transform, you can perform transforms with precisions without holding Ctrl:



You may want to read about performing transforms with precision in manual.